Tool for removing an orthodontic onlay that has been cemented to the front surface of a tooth

ABSTRACT

A tool for removing an orthodontic onlay or bracket from a tooth to which it has been cemented. The tool comprises pliers, having a pair of pivoted jaws and handles. One of the jaws has a raised pad having a resilient surface that is placed against the edge of the tooth, and the other jaw has a hard metal insert shaped to provide a chisel portion with a sharp edge for getting in between the tooth and the onlay. When the handles are forced together, the jaws move toward each other and the chisel portion separates the onlay or bracket from the tooth.

United States Patent Northcutt Sept. 4, 1973 Primary Examiner- RobertPcshock Attorney-William E. Schuyler, [)ale H. Hoscheit etal.

[57] ABSTRACT A tool for removing an orthodontic onlay or bracket from atooth to which it has been cemented. The tool comprises pliers, having apair of pivoted jaws and handles. One of the jaws has a raised padhaving a resilient surface that is placed against the edge of the tooth,and the other jaw has a hard metal insert shaped to provide a chiselportion with a sharp edge for getting in be tween the tooth and theonlay. When the handles are forced together, the jaws move toward eachother and the chisel portion separates the onlay or bracket from thetooth.

4 Claims, 4 Drawing Figures Patentd Sept. 4, 1973 FIG TOOL FOR REMOVTNGAN ORTHODONTIC ONILAY THAT HAS BEEN CEMENTED TO THE FRONT SURFACE OF ATOOTH BACKGROUND OF THE INVENTION The use of onlays cemented to a toothis new. One problem presented by such orthodontic appliances is that notonly must the onlay be cemented to the tooth but that eventually it mustbe removed from it. There is no tool known which can accomplish thisfunction efficiently.

SUMMARY OF THE INVENTION The invention comprises a pliers having a pairof pivoted jaws and a pair of handles. One of the jaws has a raised padwith a resilient surface, and this jaw is placed against the edge of thetooth to prevent chipping or fracturing of the tooth. The other jaw hasan insert of hard metal which is shaped to provide a chisel portion witha sharp edge and a forward chisel surface that is shaped concavely toapproximate the surface matching the tooth. It projects toward the padand in use rests against the pad when the jaws have been fully closedtogether. During use, the pad is seated on the edge of the tooth and thesharp member is located just above the dental onlay and then is moveddown in between the onlay and the tooth where the cement is. The forcingtogether of the handles forces the jaws to move together, and as thejaws move toward each other the chisel-like tool scrapes the onlay fromthe tooth.

Other objects and advantages of the invention will appear from thefollowing description of a preferred embodiment.

In the drawings:

FIG. l is a view in side elevation of a dental onlay removal toolembodying the principles of the invention.

FIG. 2 is an enlarged fragmentary view of the two jaws in the positionwhere they are closed against each other.

FIG. 3 is a view in section taken along the line 3-3 in FIG. 2.

FIG. 4 is a view similar to FIG. 3 but with the tool being used toremove an onlay from the tooth just at the commencement of the removaloperation.

DESCRIPTION OF A PREFERRED EMBODIMENT A tool 110 embodying theprinciples of the invention is shown in FIG. ll. It comprises twomembers 11 and 12 which cooperate with a pivot 13 to provide a pair ofpivoted jaws M and 115 and a pair of handles M and 17. Movement of thehandles 16 and 17 toward each other causes the jaws 141 and 115 to movetoward each other, and movement of the handles 16 and 17 away from eachother opens the jaws M and 115. If desired, a spring 13 may be usedbetween the handles in and 117 to urge them apart normally, the springR8 being held in place by projections or posts 19 and 190 on the handlesl6 and 1111.

The jaw M has an upstanding portion 20 (see FIG. 3) which is preferablyround and is provided with a pad 21 which rests on its upper surface 22and covers its side walls 23 so that the pad 21 itself has a flat upperresilient portion 24 and a cylindrical resilient portion 25. Thisprovides a gentle rest that can be held firmly against the edge 26 of atooth 27 as shown in FIG. 4, thereby preventing chipping or fracture ofthe tooth when closing pressure is applied later. The tooth 27 in FIG. 4has a dental onlay 28, which may be plastic, held to it by cement 29.The rear surface of the onlay 28 is shaped approximately like the frontsurface 30 of the tooth 27.

The jaw 115 of the pliers is provided with an insert 311 of hard metalsuch as tungsten carbide. This insert 311 has an anchor portion 32 thatis secured as by braising to a socket 33 and a forward portion 34 whichprojects downwardly and has a sharp lower edge 35 with a forward surfaceas. This surface 36 may be flat or it may approximate the curve of thefront surface 30 of the tooth 27 In use, the jaws M and 15 are firstspread apart somewhat, and the jaw 15 is placed below the tooth 27 withthe pad 21 located so that its upper surface 24 firmly engages thetooths edge 26. The resiliency of the pad 211 helps achieve thisengagement. The upper jaw 15 is open wide enough so that the insertmember 31 has its edge 35 slightly above the onlay 23. By urging thehandles l6 and 17 toward each other, the edge 35 is then moved down tothe top edge 37 of the onlay 28 and in between it and the surface 30 ofthe tooth, so that the edge 35 engages the cement 29. As the edge 35continues to be moved down firmly, it cuts into the cement 29, which isa somewhat brittle material such as epoxy resin and forms a cleavageplane, and the edge 35 thus pries the onlay 28 from the tooth surface30. The interface of the cement 29 with the tooth 27 is far less strongthan the enamel on the surface of the tooth 27, and the cement 29 is ofcourse far weaker than the tungsten carbide of the insert 3E, and thedownward movement of the edge 35 causes the onlay 23 to come off veryrapidly and cleanly. The tool it) directs the applied force specificallyto the cleavage plane (ji.e., the cement) and not at the enamel.Thousands of tests have been made using instruments embodying theprinciples of the invention, and there has never been any damage to theenamel. The line of least resistance is the cement-totooth interface,and so the separation takes place there.

To those skilled in the art to which this invention re lates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

I claim:

1. A tool for removing an orthodontic onlay that has been cemented tothe front surface of a tooth, comprising pliers having a pair of pivotedjaws and a pair of handles, a first said jaw terminating in a resilientpad, and a second said jaw terminating in a hard chisel portion with asharp fiat edge approximately the width of an onlay projecting towardsaid pad and resting against said pad when said jaws are closedtogether,

whereby said pliers during use are positioned with said first jaw havingits pad seated on the biting edge of said tooth and with said second jawagainst the surface of said tooth and said sharp edge is moved towardsaid pad in between said onlay arid said tooth to cleave said onlay fromsaid tooth along the cement-tooth interface.

2. The tool of claim 1 having spring means anchored to said handles forspring loading said handles away from each other.

the front surface of a tooth and is approximately the width of the onlayprojecting toward said pad and resting against said pad when said jawsare closed together,

whereby said pliers during use are positioned with said first jaw havingits pad seated on the biting edge of said tooth and with said second jawagainst the surface of said tooth and said sharp edge is moved towardsaid pad in between said onlay and said tooth to cleave said onlay fromsaid tooth along the cement-tooth interface.

I f! t 19!

1. A tool for removing an orthodontic onlay that has been cemented tothe front surface of a tooth, comprising pliers having a pair of pivotedjaws and a pair of handles, a first said jaw terminating in a resilientpad, and a second said jaw terminating in a hard chisel portion with asharp flat edge approximately the width of an onlay projecting towardsaid pad and resting against said pad when said jaws are closedtogether, whereby said pliers during use are positioned with said firstjaw having its pad seated on the biting edge of said tooth and with saidsecond jaw against the surface of said tooth and said sharp edge ismoved toward said pad in between said onlay and said tooth to cleavesaid onlay from said tooth along the cement-tooth interface.
 2. The toolof claim 1 having spring means anchored to said handles for springloading said handles away from each other.
 3. The tool of claim 1wherein facing inner surfaces of said handles have posts projectingtherefrom and a coil spring anchored at said posts and urging saidhandles apart from each other.
 4. A tool for removing an orthodonticonlay that has been cemented to the front surface of a tooth, comprisingpliers having a pair of pivoted jaws and a pair of handles, a first saidjaw terminating in a resilient pad, and a second said jaw terminating ina hard chisel portion with a sharp edge that approximates the curve ofthe front surface of a tooth and is approximately the width of the onlayprojecting toward said pad and resting agaInst said pad when said jawsare closed together, whereby said pliers during use are positioned withsaid first jaw having its pad seated on the biting edge of said toothand with said second jaw against the surface of said tooth and saidsharp edge is moved toward said pad in between said onlay and said toothto cleave said onlay from said tooth along the cement-tooth interface.